The Landmarks Preservation Commission voted unanimously on Tuesday to designate the I.M. Pei-designed Silver Towers complex of three high-rise residential buildings and its central plaza with its 36-foot-tall sculpture of Picasso’s “Portrait of Sylvette.”

The designation, however, does not extend to the rest of the New York University-owned superblock that includes the Morton Williams supermarket on LaGuardia Place and the university’s Coles Sports Center on Mercer St.

The landmark designation protects the 30-story-tall Silver Towers 1 and 2 and 505 LaGuardia Place, all built in 1966, and the concrete version of Picasso’s “Sylvette,” executed in 1970 by the Norwegian sculptor Carl Nesjar.

Originally known as University Village, the complex is set on the 5-acre superblock bounded by Bleecker and W. Houston Sts. and LaGuardia Place and Mercer St.

“It’s widely known as one of the finest Modern residential complexes in the city,” said L.P.C. Chairperson Robert Tierney.

Andrew Berman, director of the Greenwich Village Society for Historic Preservation, hailed the plaza’s designation, which makes it unlikely that New York University could put up another building in the complex.

“It’s a great conclusion to our efforts over the past five years to secure landmark protection for the complex, especially in view of N.Y.U.’s proposal to build a 40-story tower in the open space at Bleecker St.,” Berman said.

The preservationist referred to an N.Y.U. rendering of potential redevelopment in the superblock as part of its N.Y.U. 2031 Plan. However, N.Y.U. did not oppose the designation at hearings earlier this year.

The commission on Tuesday also designated the five-story former Bauman Bros. furniture and carpet store at 22-26 E. 14th St., completed in 1881. The New School acquired the building’s top four stories in 1979, and the ground floor is devoted to retail.

At the same time, the commission conferred landmark designation on the seven-story loft building at 144 W. 14th St., completed in 1896 and serving as Pratt Institute’s Manhattan campus since 2001.

Also designated on Tuesday was the Guardian Life four-story annex, at 108-116 E. 18th St. and 105-117 E. 17th St., designed by Skidmore, Owings & Merrill and completed in 1963. The Related Companies now owns the building, which is devoted to office space.